The present invention relates to the recovery of hydrocarbons (especially oil) from underground formations (particularly low permeability formations).
U.S. Pat. No. 5,085,276 ("Rivas") discloses the production of oil from low permeability formations by sequential steam fracturing. Rivas reports that "heating of the formation water and its `flashing` from a liquid to a gas phase upon reducing wellbore pressures when returning to the production mode produces significantly increased quantities of oil from the formation to the wellbore." (Rivas, column 3, lines 39-44.) Furthermore, Rivas states that "the `flashing` effect [continues] within the wellbore, as pressure therein reduces, thus aiding the flow of fluids to the surface for recovery from the wellbore." (Rivas, column 3, lines 44-47.)